''******************************************************************* ''* Simple Asynchronous Serial Driver v1.4 * ''* Authors: Chip Gracey, Phil Pilgrim, Jon Williams, Jeff Martin * ''* Copyright (c) 2006 Parallax, Inc. * ''* See end of file for terms of use. * ''******************************************************************* '' '' Performs asynchronous serial input/output at low baud rates (~19.2K or lower) using high-level code '' in a blocking fashion (ie: single-cog (serial-process) rather than multi-cog (parallel-process)). '' '' To perform asynchronous serial communication as a parallel process, use the FullDuplexSerial object instead. '' '' '' v1.4 - Feb 3, 2014 Fixed Init method to initialize txPin (if specified and not bi-directional communication). '' Previous versions did not initialize txPin until transmission. '' v1.3 - May 7, 2009 - Updated by Jeff Martin to fix rx method bug, noted by Mike Green and others, where uninitialized '' variable would mangle received byte. '' v1.2 - Mar 26, 2008 - Updated by Jeff Martin to conform to Propeller object initialization standards and compress by 11 longs. '' v1.1 - Apr 29, 2006 - Updated by Jon Williams for consistency. '' '' '' The init method MUST be called before the first use of this object. '' Optionally call finalize after final use to release transmit pin. '' '' Tested to 19.2 kbaud with clkfreq of 80 MHz (5 MHz crystal, 16x PLL) { VAR long sin, sout, inverted, bitTime, rxOkay, txOkay } DAT sin long 0 sout long 0 inverted long 0 bitTime long 0 rxOkay long 0 txOkay long 0 PUB init(rxPin, txPin, baud): Okay {{Call this method before first use of object to initialize pins and baud rate. • For true mode (start bit = 0), use positive baud value. Ex: serial.init(0, 1, 9600) For inverted mode (start bit = 1), use negative baud value. Ex: serial.init(0, 1, -9600) • Specify -1 for "unused" rxPin or txPin if only one-way communication desired. • Specify same value for rxPin and txPin for bi-directional communication on that pin and connect a pull-up/pull-down resistor to that pin (depending on true/inverted mode) since pin will set it to hi-z (input) at the end of transmission to avoid electrical conflicts. See "Same-Pin (Bi-Directional)" examples, below. EXAMPLES: Standard Two-Pin Bi-Directional True/Inverted Modes Standard One-Pin Uni-Directional True/Inverted Mode Ex: serial.init(0, 1, ±9600) Ex: serial.init(0, -1, ±9600) -or- serial.init(-1, 0, ±9600) ┌────────────┐ ┌──────────┐ ┌────────────┐ ┌──────────┐ │Propeller P0├─────────────┤I/O Device│ │Propeller P0├───────────────┤I/O Device│ │ P1├─────────────┤ │ └────────────┘ └──────────┘ └────────────┘ └──────────┘ Same-Pin (Bi-Directional) True Mode Same-Pin (Bi-Directional) Inverted Mode Ex: serial.init(0, 0, 9600) Ex: serial.init(0, 0, -9600)  ┌────────────┐ ┌──────────┐ │ │Propeller P0├─────┳─────┤I/O Device│  4.7 kΩ └────────────┘ │ └──────────┘ ┌────────────┐ │ ┌──────────┐  4.7 kΩ │Propeller P0├─────┻─────┤I/O Device│ │ └────────────┘ └──────────┘  }} finalize ' clean-up if restart rxOkay := rxPin > -1 ' receiving? txOkay := txPin > -1 ' transmitting? sin := rxPin & $1F ' set rx pin sout := txPin & $1F ' set tx pin inverted := baud < 0 ' set inverted flag bitTime := clkfreq / ||baud ' calculate serial bit time if txOkay and (sin <> sout) ' if txPin specified and not Bi-Directional communication; initialize sout pin outa[sout] := !inverted ' set idle state dira[sout]~~ ' make tx pin an output return rxOkay | TxOkay PUB finalize {{Call this method after final use of object to release transmit pin.}} if txOkay ' if tx enabled dira[sout]~ ' float tx pin rxOkay := txOkay := false PUB rx: rxByte | t {{ Receive a byte; blocks caller until byte received. }} if rxOkay dira[sin]~ ' make rx pin an input waitpeq(inverted & |< sin, |< sin, 0) ' wait for start bit t := cnt + bitTime >> 1 ' sync + 1/2 bit repeat 8 waitcnt(t += bitTime) ' wait for middle of bit rxByte := ina[sin] << 7 | rxByte >> 1 ' sample bit waitcnt(t + bitTime) ' allow for stop bit rxByte := (rxByte ^ inverted) & $FF ' adjust for mode and strip off high bits PUB tx(txByte) | t {{ Transmit a byte; blocks caller until byte transmitted. }} if txOkay outa[sout] := !inverted ' set idle state dira[sout]~~ ' make tx pin an output txByte := ((txByte | $100) << 2) ^ inverted ' add stop bit, set mode t := cnt ' sync repeat 10 ' start + eight data bits + stop waitcnt(t += bitTime) ' wait bit time outa[sout] := (txByte >>= 1) & 1 ' output bit (true mode) if sout == sin dira[sout]~ ' release to pull-up/pull-down PUB str(strAddr) {{ Transmit z-string at strAddr; blocks caller until string transmitted. }} if txOkay repeat strsize(strAddr) ' for each character in string tx(byte[strAddr++]) ' write the character PUB dec(value) | i if value < 0 tx("-") if value == NEGX tx("2") value := -(value + 2_000_000_000) result := -1 else value := -value i := 1_000_000_000 repeat 10 if value => i tx(value / i + "0") value //= i result := -1 elseif result or i == 1 tx("0") i /= 10 {{ ┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ │ TERMS OF USE: MIT License │ ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤ │Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation │ │files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, │ │modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software│ │is furnished to do so, subject to the following conditions: │ │ │ │The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.│ │ │ │THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE │ │WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR │ │COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, │ │ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │ └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ }}